Rename state_name to get_state_name

A bit more consistent naming.  Rename is possible because the method
hasn't been part of a release yet.
diff --git a/tests/test_ssl.py b/tests/test_ssl.py
index da313f7..8040c97 100644
--- a/tests/test_ssl.py
+++ b/tests/test_ssl.py
@@ -2353,8 +2353,8 @@
         server = self._loopbackServerFactory(server)
         client = self._loopbackClientFactory(client)
 
-        assert b"before/accept initialization" == server.state_string()
-        assert b"before/connect initialization" == client.state_string()
+        assert b"before/accept initialization" == server.get_state_string()
+        assert b"before/connect initialization" == client.get_state_string()
 
     def test_app_data_wrong_args(self):
         """